Feeding device



Jan. 8, 1952 l4 ml L. A.4 MAxsoN 2,581,805

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Patented Jan. 8, 1952 FEEDIN G DEVICE `Louis A. Maxson, Claremont, N. H., assignor to Joy Manufacturing Company,a corporation of Pennsylvania Application October 2, 1944, Serial No. 556,801V

This invention relates to feeding devices and more lparticularly to improved feeding devices embodying automatic control means for regulating the feed in accordance withA the requirements of the Work.

The improved automatic feeding device is especially adapted for use ,in drifter type rock drills wherein the drilling tool is guided for feeding movement along a guiding support, and a motor driven feed screw journaled on the support engages a non-rotatable feed nut carried by the drill tool. In such drills it is desirable to regulate the feed a-utomatically'in accordance with the requirements of the work during drilling. In other words, it is desirableto slow down the feed when the resistance to penetration of the work by the drill steel becomes excessive and automatically to speed up the feed when the resistance to penetration ofthe work by the drill steel decreases. Broadly, this improved automatic control of the feed may be accomplished by mounting the feed screw of theifeeding( device for limited axial movement with respect to the guiding support under the control of yieldable means and by regulating the rate of feed4 automatically in accordance with the axial position of the feed screw. In a preferred embodiment of the invention the yieldable means may consist of a compression spring pressing the feed screw` in one direction, and the automatic control means may include a brake for resisting rotation of the feed screw. y In such embodiment mentioned, the limited axial movement of the feed screw with respect to the guiding support is employed automatically to control the feed; and axial movement of the screw operates the automatic control means for regulating screw rotation by frictional means. Other embodiments such as the use of a yieldingly mounted feed screw controlling its own rotation through lts yieldingwill readily occur to those skilled in the art, and it will be appreciated that it is not essential that a feed screw be employed, and that, for example, a yieldingly mounted rack whose give controls the rotation of an associated pinion to effect feed is within the broad concept of my invention, which from one primary aspect may be said to comprise relatively rotatable feeding elements, one of whichmoves along the other during feeding and the latter one of which is yieldingly mounted and through its yielding controls the feeding force exerted.

An object of the present invention is to provide an improved automatic feeding device. Another object is to provide. an improved'autosciaims. (ci. c55- 45) matic feeding device embodying improved control means whereby the feed is controlled automatically in accordance with the requirements of the work during drilling. Still another object is to provide an improved feeding mechanism comprising relatively rotatable feeding elements one of which is elongated and the other of which is power rotated to cause its movement along the first, and the first of which is yieldingly mounted for longitudinal movement, and through its yielding controls the relative rotation between said feeding elements which effects feeding. A further object is to provide an improved feedingdevice embodying afeed screw mounted for limited axial movement and having improved automatic control means operated by axial movement of the screw for regulating screw rotation. A still further object is to provide an improved feeding device for a rock drill of the mounted drifter type wherein the feed is controlled automatically in accordance with the resistance to penetration of the Work by the drill steel. Still another object is to provide an improved automatic feed control means which embodies a brake for resisting rotation of the feed screw to control the rate of feed. Yet another object is to provide an improved automatic control means which is controlled automatically by the axial movement of the feed screw for regulating rotation of the feed screw by its driving means. Other objects and advantages of the invention Will, however, hereinafter more'fully appear. l

In the accompanying drawing there is shown for purposes lof illustrationA one form which the invention may assume in practice.

In this drawing: I

Fig. 1 is a side elevational view of a rock drill in which an illustrative form of the invention is incorporated, parts being shown in section to illustrate structural details.

Fig. 2 is an enlarged longitudinal vertical sectional view through the improved feeding dev1ce. Y

In this illustrative embodiment of the invention, the improved feeding device is embodied in a mounted rock drill ofthe motor feed, drifter type.l

The rock drill may assume various forms, but may for illustration be generally similar to that shown in the patent to one J. C. Curtis, No. 2,320,571, granted June l, 1943, and herein is shown as including a drilling motor I preferably ofthe pressure fluid actuated, hammer type for percussively actuating` a drill steel 2. Flow of pressure fluid to the drilling motor to effect actuation of the hammer piston thereof is controlled by a usual throttle valve mechanism 3. The drilling motor is guided'for movement back and forth along the guideways of a guiding support or guide shell 4. A rotatable feed screw extends longitudinally of the guide shell and is journaled thereon and slidable relative thereto, and this feed screw engages a non-rotatable feed nut .6 carried by the cylinder of the drilling motor. A reversible feeding motor 'I is attached to the rear end of the guide shell and is operatively connected to the feed screw 5 for driving the latter, as hereinafter .more fully described. The feed motor is also of the pressure fluidv actuated type, and the flow of pressure iiuid thereto is controlled by a usual control valve B., In the illustrative embodiment of the invention, the feed screw 5 is yieldingly mounted on the lguide shell d for limited axial movement. The feed screw near its rear end has a flange 9 which engages a thrust bearing I0. Encircling the screw and interposed b-etween the rear surface of the thrust bearing and a shoulder II on an adjustable follower I2 is a coil spring I3 which constantly urges the feed screw toward its foremost position. This spring is held under substantial compression, vso that it will not yield until a substantial feeding pressure is attained. Its compression may be altered if up or down hole drilling is to be done, being increased for up hole drilling and decreased for down hole drilling. The adjustable follower I2 is lthreaded at I4 within a bore VI5 in a casing I6 attached by bolts n to the guide Shen. The motor 1 has a casing I8 which is also attached by the bolts I1 to the guide shell. The follower I2 may be adjusted within the bore I5 to vary the compression of the spring. Secured to a rearward extension I9 of the feed screw is a pressure plate 20 for engaging the end disk of a Aseries of interleaved friction disks 2| vand 22 of a brake. The outer disks 2l are keyed to the casing I6, while the inner disks 22 `are keyed to a sleeve 23 in turn keyed at 24 to the feed screw extension I9. The rear inner `disk engages a shoulder 25 on the casing I6. When the feed screw is moved axially in a rearward direction against the section rof the coil spring I3, the

pressure plate 20 moves the series of friction i disks together partially or completely to apply the brake thereby to frictionally resist rotation of the feed screw. The rear Aend ofv theV feed screw extension I9 'is slidably supported by and is splined at 26 to a, hub 21 of a rotary distributing valve 28. As described in the patent above referred to, the valve 28 controls the distribution of pressure fluid to the feed motor 1. It is accordingly evident that the friction brake is controlled automatically by the raxial movement of the feed screw for regulating rotation vofthe screw by the feed motor.

The general mode of operation of the improved feeding device will be clearly apparent from the description given. The guiding support 'or guide shell ll may be mounted on a suitable rsupport near the working face in a well known'mannen and the Vdrilling motor I may then be started under the control ofthe valve mechanism 3 to effect actuation of the drill vsteel 2.

trol of the valve mechanism 8 to effect rotation of the feed screw 5 to feed the drilling motor forwardly along the shell guideways to bring the `cutting end of the 'drill steel against the work.

The feed 'motor l may then be operated under 'the con- 4 As the drilling of a hole in the working face progresses and resistance to penetration of the work by the drill steel builds up, the feed screw 5 moves axially in a rearward direction with respect to the guide shell against the action of the coil spring I3, and, as a result, the brake 2I, 22- Vis applied frictionally to resist rotation of the feed` screw. When the resistance to penetration of the work by the drill steel becomes excessive, the brake 2|, 22 is fully applied and v"feed-screw is moved axially in a forward direction by the coilrspring, and as a result, the brake is partially orwholly released. Accordingly, the axial :movement-.vof the feed screw under the controlof the coil spring automatically regulates rotation of the feed screw by its driving motor.

As a result of this invention, an improved feeding device is provided whereby the feed is controlled automatically by the varying degrees of resista-nce of penetration of the work by the drill steel. It will further be evident that -by the provision of the automatic feed controlling means embodying a feeding element, as illustrated -a feed screw, mounted for limited axial movement, an extremely sensitive control of feed is attained. The device is simple and rugged in construction and may readily be embodied in a conventional rock drill with little modification of the drill structure. Other uses and advantages of the invention will be clearly appar-ent to those skilled in the art.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown 'for purposes of i1- lustrat-ion and that the invention may be modilied and embodied in various other forms without vdeparting from vits spirit or the scope of the appended claims.

What I claim as new Aand desire to secure by Letters Patent is:

l. In' a feeding device, a'rotatable feed screw having a feed nut thereon and threadedly engaged therewith 'and movable along said feed screw in -one direction or the other by rotation of said'feed screw in one or the other direction, means for mounting said feed screw for limited axial movement, means .for yieldingly maintaining said feed screw in aforward position relative to its mounting meansv except 'when excessive feeding pressures exist, means for driving said screw to cause the-same to move said feed nut therealong, and Vmeans controlled automatically by rearward axial movement of said screw on its mounting means for braking rotation of said'scre-w including a brake k.for said feed screw and means for applying said brake including `a brake applying element operatively connected with said feed screw for movement by the latter, as the latter moves rearwardly 'against the resistance of said yieldingly maintaining means, -to eifect brak-e application.

2. In a drillingapparatus, `means providing a guideway, relatively rotatable feeding elements lcooperating on relative rotation to -efiect'feeding-of one of `said velements longitudinally of said fguideway, the other of said elements extending lengthwise of said guideway and mounted for limited yielding -lengthwise rearwardly relative to said rguideway, and. feed controlling :means governed by `such ,limited lengthwise .yielding of the relative rotation between said elements, said feed controlling means comprising a brake ar-V ranged to effect, upon application thereof, a frictional resistance to such relative rotation and including at least one braking element surrounding said yieldingly mounted element and means for causing said brake to effect a braking of such relative rotation upon rearward yielding of said yieldingly mounted element.

3. In a drilling apparatus, means providing a guideway, relatively rotatable feeding elements cooperating on relative rotation to effect feeding of one of said elements longitudinally of said guideway, a device to be fed guided by said guideway, the other of said elements elongated in the direction of feed and the first so connected to said device that the latter is fed as said v iirst element moves along the elongated element,

means for supporting said elongated element for '.5

limited rearward yielding movement longitudinally thereof, and braking means controlled by the yielding of said elongated element for controlling the relative rotation between said elements by resisting such relative rotation, said braking means including means providing a friction surface coaxial with said elongated element and Vstationary as regards rotation, coacting means providing a friction surface rotatable with said elongated element and means for effecting increasing frictional engagement between said surfaces actuated by rearward yielding movement oi' said elongated element.

4. In a feeding device, cooperating relatively rotatable, mechanically interengaged, feeding elements cooperating on relative rotation to effect feed, means for yieldingly mounting one of said elements for limited axial movement, motor operated means for effecting relative rotation between said elements, and braking means controlled automatically by rearward axial movement of said yieldingly axially movable element for imposing a progressively increasing resistance to relative rotation of said elements as` said yieldingly mounted element yieldsincreasingly, including a brake connected to retard such relative rotation and actuating means therefor connected to said yieldingly movable element for actuation by the latter.

`5. In a drilling apparatus, in combination, a support, a drilling tool guided for movement therealong, means for feeding said drilling tool along said support including cooperating relatively rotatable, mechanically interengaged feeding elements, one of which is yieldingly mounted on said support for limited rearward movement longitudinally relative thereto upon the development of excessive feeding forces, and the other element, which coacts With said longitudinally movable element, being carried by said drilling tool, a rotary feeding motor, driving connections driven by said motor for effecting relative rotation between said elements, and brake means having an actuating connection with said longitudinally movable element and applicable by longitudinal movement of said longitudinally movable element upon rearward yielding of the latter for braking motor rotation.

6. In a rock drill, a guide shell, a drilling motor movable along the guideways of said shell, a rotary feeding motor mounted at the rear end of said shell, a rotatable feed screw extending longitudinally of said shell and operatively connected to said motor for rotation by the latter, a feed nut coacting with said screw and carried by the drilling motor, means for yieldingly mounting' said screw on said shell for limited rearward axial movement normally maintaining the same in a forward position when a feeding force of less than a predetermined value is being exerted, and frictional resistance means for automatically controlling the rate of motor rotation comprising a frictional resistance device connected with, and actuated by rearward axial movement of, said screw. y

7. In a rock drill, a guide shell, a drilling motor movable along the guideways of said shell, a rotary feeding motor mounted at the rear end of said shell, a rotatable feed screw extending longitudinally of said shell and operatively connected to said motor for rotation by the latter, a feed nut coacting with said screw and carried by the drilling motor, means for yieldingly mounting said screw on said shell for limited rearward axial movement relative to said shell, and braking means for automatically controlling the rate of screw rotation comprising a brake applicable to retard screw rotation and connected with, and applied by rearward axial movement of, said screw.

8. In a feeding device, the combination of a support and a drilling tool movable therealong, a rotary feeding motor for said drilling tool, a. feed screw carried by said support and yieldable longitudinally relative thereto rearwardly when excessive feed resistance is encountered, a feed nut coacting with said screw and carried by said drilling tool, slip driving connections between said motor and said feed screw enabling longitudinal relative movement between them, and frictional resistance means at the feed screw side of said slip connections having actuating means connected with said feed screw for movement thereby and operable by such longitudinal movement of said screw for controlling driving of said screw by said motor.

LOUIS A. MAXSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,554,766 Slater Sept. 22, 1925 1,818,393 Hansen Aug. 11, 1931 2,208,751 Dicker, Sr June 23, 1940 2,221,118 Smith et al Nov. 12, 1940 2,223,533 Schorle Dec. 3, 1940 2,236,700 Slater Apr. 1, 1941 2,265,444 Morrison et al. Dec. 9, 1941 2,320,571 Curtis June 1, 1943 

